The serotonergic neural system of the brain has been shown to influence a variety of physiologic functions which manifest themselves in a variety of disorders such as eating disorders, schizophrenia, neuralgia, and addiction disorders; depression, obsessive compulsive disorders, panic disorders, anxiety, sexual dysfunctions caused by the central nervous system and disturbances in sleep and the absorption of food, alcoholism, pain, memory deficits, unipolar depression, dysthymia, bipolar depression, treatment-resistant depression, depression in the medically ill, panic disorder, obsessive-compulsive disorder, eating disorders, social phobia, premenstrual dysphoric disorder, pulmonary hypertension and systemic hypertension.
Type 2 serotonin inhibitors (5-HT2) mediate the action of several drugs used in treating, e.g., schizophrenia, feeding disorders, perception, depression, migraines, hypertension, anxiety, hallucinations, and gastrointestinal dysfunctions. The 5-HT2A, B or C receptor subtypes show considerable homology at genetic, structural and functional levels, and all are G-protein coupled receptors (GPCRs.) 5-HT2A receptors have been found in high density in the cerebral cortex and in interneuronal regions, as well as, in lower density, in the hippocampus, striatum, other cerebral regions, platelets, and vascular and uterine smooth muscle.
5-HT2B receptors are widely distributed in mammalian peripheral tissue, e.g., heart, skeletal and vascular muscle, adipose tissue, intestine, ovary, uterus, testis, liver, lung, pancreas, trachea, spleen, thymus, thyroid, prostate and salivary gland, as well as in the CNS, e.g., in the cerebral cortex and the whole brain. Serotonin binds to the receptor with an affinity of 2-10 nM (Rothman et al. 2000; Kursar et al. 1994). 5-HT2B receptors are present in many vascular beds and have been localized to both vascular smooth muscle and vascular endothelial cells in humans (Ullmer et al. 1995; Marcos et al. 2004). The receptor was characterized initially in the rat gastric (fundus) smooth muscle cells (SMC) as the receptor responsible mediating serotonin (5-HT)-induced contraction in this tissue (Kursar et al. 1994).